The following is not a full list of side effects. Side effects cannot be anticipated. If any develop or change in intensity, tell your healthcare provider as soon as possible. Only your healthcare provider can determine if it is safe for you to continue taking this medication.
Due to the risk of serious, life-threatening breathing problems, do not use Fentora unless you are regularly using another narcotic painkiller around-the-clock for at least one week or longer for your cancer pain and your body is used to these medicines. Also, do not use Fentora to treat pain after surgery if the pain is mild or not expected to last for a long period (including headaches or migraines). Tell your healthcare provider right away if you are breathing more slowly than usual; are experiencing shallow breathing (little chest movement while breathing); or if you feel faint, dizzy, confused, or have any other unusual symptoms.
Keep Fentora in a safe place, away from children. Accidental use may result in serious harm and may be life-threatening.
Fentora has abuse potential. If you have concerns, talk to your healthcare provider for more information about abuse and addiction. Do not share Fentora with others and take steps to protect Fentora from theft or misuse.
Fentora is available only through a program called the Transmucosal Immediate Release Fentanyl (TIRF) Risk Evaluation and Mitigation Strategy (REMS) Access Program. Under this program, you must talk to your healthcare provider, understand the benefits and risks of Fentora, agree to all the instructions, and sign the Patient-Prescriber Agreement form in order to receive Fentora.
More common side effects may include: nausea; dizziness; vomiting; tiredness; low red blood cell counts; constipation; swelling in your arms, hands, legs, or feet; weakness; dehydration; headache.
Less common side effects may include:
Fentora may decrease your heart rate.
Fentora may cause pain, irritation, or sores at the application site (on your gum, on the inside of your cheek, or under your tongue). Tell your healthcare provider if this is a problem for you.